Tension control device



Sept. 11, 1962 F. L. LUNTZ ETAL TENSION CONTROL DEVICE Filed Aug. 11, 1959' Z if? 7/ /4 a A Z if E 5 if v [6 Q I 27 INVENTORS FRED L.LUNTZ & 1.7 4 VINCENT E.LYNCH I GQ ATTORNEYS.

States Unite "fice 3,053,474 TENSION CONTROL DEVICE Fred L. Luntz, Brooklyn, and Vincent E. Lynch, Albertson, N.Y., assignors to Telephonics Corporation, Huntington, N.Y., a corporation of New York Filed Aug. 11, 1959, Ser. No. 833,103 6 Claims. (Cl. 242-150) The present invention relates to tensioning devices and, more particularly, to a device to develop controllable tension in a moving thread or strand.

A principal object of the invention is to provide a new and improved structural arrangement for a tension control device.

It is also an object of the invention to provide a tension control device that permits greater accuracy of adjustment of tension on a thread or strand and provide a magnetic circuit of greater efficiency, thereby requiring smaller magnitudes of control current.

Generally, the device of the invention provides a new and greatly simplified structural arrangement for a strand tensioning device to obtain greater efliciency in manufacture and in operation and to obtain greater sensitivity of adjustment for the tension to be applied. A first member having a surface to cooperate with a disc is provided with an electrical coil and arranged so that a gap of fixed dimensions is formed between two magnetic poles. The disc is formed of a magnetizable material so that it is urged toward the poles under the influence of a magnetic field developed by the electrical coil.

A device in accordance with the invention is operable with all forms of strand material, either textile or otherwise. Moreover, the tensiouing device of the invention is adaptable for operation automatically to maintain a predetermined uniform tension on the strand as the linear speed of the strand is varied. In addition, the smaller magnitude of electric current required by the increased efficiency of the magnetic circuit greatly simplifies the electric installation problems.

Some examples of uses to which the device of the invention is adaptable are with warpers, quill winders, cone and package winders, doublers, twisters and circular stocking knitting machines. In such uses the device fits into standard holding brackets usually found on such machines.

In Winding machines of the type, for example, which operate in such a manner that as the winding progresses and the package increases in circumference, the yarn feeds at an accelerated rate. Consequently, a device constructed in accordance with the invention, being responsive to relatively small electric current changes, is uniquely adapted to provide incrementally small changes in the tension applied to the strand to maintain the tension at a predetermined constant value.

Other objects and advantages of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose by way of example the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawngs:

FIG. 1 is an exploded view in perspective of a preferred form of the invention;

FIG. 2 is a view in elevation of the device shown in FIG. 1;

FIG. 3 is a plan view of the device as shown in FIG. 2; and

' FIG. 4 is a cross-sectional view taken along the lines 44 of FIG. 3.

Referrings now to one form of the invention as shownin the drawings, the tensioning device is provided with a cup-shaped housing 11 formed of a suitable magnetizable material, such as, for example, soft iron or steel. The rim of the housing 11 is turned up to provide the cup-shaped appearance and to form one annular pole 12 of an electromagnet. A centrally located aperture 13 in the housing 11 provides means for assembly, as will appear from the description to follow.

A circular plate 14- is formed of a magnetizable material which, if desired, may be the same material that forms the cup-shaped housing 1 1 and is provided with a depending hub 15 having a centrally located aperture 16 to match the aperture 13. In addition, the hub 15 is of suficient length to bear aganst the inner surface of the cup-shaped housing '11.

The peripheral portion of the circular plate 14 is enlarged to provide a second magnetic pole17, and the radius of the circular plate or pole member 14 is smaller than the radius of the housing 11 so that a gap 18 is formed between the two poles 12 and 17.

A ring 19 of non-magnetizable material such as brass is press-fitted around the peripheral portion of the circular plate 14 and is provided with an annular downwardly facing groove 20 to receive the magnetic pole 12. With the plate 14 and ring 19 assembled together with .the cup-shaped housing 11, an electrical coil 21, which is wound directly on the hub 15, provides an electromagnetic source to magnetize the loop including the hub 15, housing 1 1, pole 12, gap 18, pole 17, and the plate 14. Electrical leads 22 protruding through an opening 23 in the housing 11 provide means for connecting a suitable voltage source (not shown) to energize the coil 21.

A freely revolvable disc 24 of magnetizable material forms a magnetic bridge across the gap 18 between the two poles 12 and '17 so that the magnetic lines of force traversing the above referred to loop will be diverted from the gap 18 to the disc 24 and back to the pole 12 across a smaller gap 25.

The dimensions of the gap 18 are selected so that even With a thread 26 in place for tensioning, as shown in FIG. 2, the gap 25 between the pole 12 and the magnetizable disc 24 is preferably smaller than the gap 18. At least, the magnetic reluctance of the gap 25 is less than the magnetic reluctance of the gap 18. In this manner, the disc 24 is urged toward the upper surface provided by the pole 17 and the ring 19 by a magnetic force which is controllable by the energization current applied to the coil 21. A post 27 formed of suitable material, for example, that known commercially under the name of Alsim-ag, is supported on the plate 14"by a threaded bolt 28 which passes through the longitudinal, central axis of the post 27 and through the apertures 13 and 16 in the housing 1 1 and hub 16, respectively. The post 27 is revolva-ble by a thread 26 passing around the post as illustrated in FIG. 3. Therefore, a nut 29 is threaded on the bolt 28 only suficiently to provide upright support for the post 27.

As best seen in FIG. 4, the inner corners 30 and 31 on the mag-net pole *1! and the disc 24, respectively, are rounded to prevent wear and possibly breakage of the thread 26 as it passes around the post 27. In addition, the outer corners 32 and 33 are canted for the same reason. I v

The above-described structural arrangement provides the advantages that the upper surface provided by the 1 pole 17 and the ring '19 can be manufactured to closer There are two primary functions provided by the ring 19, one being that both of the gaps 18 and 25 can be formed accurately during manufacture and the other being the provision of increased surface area against which the disc 24 may apply tension to a thread. Due to the accuracy of dimensions for the gaps 18 and 25, the control over the tension to be applied is adjusted to a greater degree of accuracy by the coil 21. An additional advantage provided by the ring 19 is that the increased surface area prevents a tendency for a thread to ride out of the device when operation is ceased.

To illustrate the greater effectiveness of a structural arrangement as provided by the present invention in obtaining accurately controlled tension in a moving thread, an applied potential of four volts produces a tension of approximately grams with devices heretofore known whereas the same potential produces a tension of approximately 100 grams with the device of the invention.

The tensioning device as described above permits a tension to be developed in a moving thread in the order of 100 grams due solely to the magnetic attraction of the disc 24. However, when the device is mounted for operation in an upright position, as illustrated in FIG. 2, higher tensions can be developed by adding weights (not shown) to the disc 24.

In operation, a thread or strand is positioned between the disc 24 and the upper surface provided by the pole 17 and ring 19, and an electric current is applied to energize the coil 21. The magnetic lines of force resulting from the energization of the coil 21 urges the disc 24 toward the surface provided by the pole 17 and the ring 19, the intensity of the magnetic attraction being controlled by varying the magnitude of the electric current. Most of the magnetic lines of force pass through the disc 24 which bridges the poles 12 and 17, thus, attracting the disc 24 to squeeze the thread or strand. Negligible lines of force pass through the gap 18 due to its greater length or reluctance compared with the length of the gap 25.

The invention has been shown by way of example only, and many modifications and variations may be made therein without departing from the spirit and scope of the invention. For example, the hub 15 may, if desired, be formed integrally with the cup-shaped housing 11, and the coil 21, therefore, will be formed directly within the housing 11 in substantially the same position as that shown in FIG. 4 of the drawings. Therefore, it is understood that the invention is not to be limited to any specified form or embodiment except in so far as such limitations are set forth in the appended claims.

We claim:

1. A device to develop controllable tension in a moving strand comprising an electromagnet including an annular coil, a housing of magnetizable material for the coil forming an annular pole of the electromagnet, a central core of magnetizable material mounted in the housing within the annular coil and magnetically coupled o to the housing, a relatively fixed annular plate of magnet izable material coupled in magnetic circuit relation to the central core and extending over at least a portion of the annular coil to form an opposite pole of the electromagnet and to define a gap of predetermined magnetic reluctance between the poles, the annular plate having an upper surface against which a moving strand is squeezed to apply tension thereto, a ring of non-magnetizable material fixedly mounted about and having an upper surface lying in a plane with said upper surface of said annular plate and extending radially therefrom to form an extension of the upper surface thereof, and a disc of magnetizable material positioned adjacent the poles of the electromagnet and in magnetic circuit relation therewith so as to be urged toward said upper surface of the annular plate and ring by the electromagnet for applying a controllable tension to a strand moving therebetween.

2. A device to develop controllable tension in a moving strand comprising an electromagnet including an annular coil, a housing of magnetizable material forming an annular pole about the annular coil, a relatively fixed annular plate of magnetizable material extending over a portion of the annular coil toward the annular pole to form an opposite pole of the electromagnet and to define a gap of predetermined magnetic reluctance, the annular plate having an upper surface against which a moving strand is squeezed to apply tension thereto, a ring of non-magnetizable material fixedly mounted about and having an upper surface lying in a plane with said upper surface of said annular plate and extending radially there from to form an extension of the upper surface thereof, a disc of magnetizable material positioned adjacent the poles of the electromagnet and in magnetic circuit relation therewith so as to be urged toward said upper surface of the annular plate and ring by the electromagnet for applying a controllable tension to a strand moving therebetween, and said ring passing between said annular pole of the electromagnet and said disc to define a working gap between said annular pole and the upper surface of said ring having a magnetic reluctance less than said predetermined magnetic reluctance.

3. A device to develop controllable tension in a moving strand comprising an electromagnet including an annular coil, a housing of magnetizable material for the coil forming an annular pole of the electromagnet, a central core of magnetizable material mounted within the annular coil and magnetically coupled to the housing, a relatively fixed annular plate of magnetizable material coupled magnetically to the central core and extending over at least a portion of the annular coil to form an opposite pole of the electromagnet and to define a gap of predetermined dimensions between the poles, the annular plate having an upper surface against which a moving strand is squeezed to apply tension thereto, a ring of non-magnetizable material fixedly mounted about and having an upper surface lying in a plane with said upper surface of said annular plate and extending radially therefrom to form an extension of the upper surface thereof, a post extending from the annular plate along a line substantially perpendicular to the plate, and a disc of magnetizable material having an aperture to receive the post so that the disc is positioned adjacent the upper surface of the annular plate and ring and in magnetic circuit relation with the poles of said electromagnet.

4. A device to develop controllable tension in a moving strand comprising an electromagnet including an annular coil, a housing of magnetizable material for the coil forming an annular pole of the electromagnet, a central core of magnetizable material mounted within the annular coil and magnetically coupled to the housing, a relatively fixed annular plate of magnetizable material coupled magnetically to the central core and extending over at least a portion of the annular coil to form an opposite pole of the electromagnet and to define a gap of predetermined magnetic reluctance between the poles, the annular plate having an upper surface against which a moving strand is squeezed to apply tension thereto, a ring of non-magnetizable material fixedly mounted about and having an upper surface lying in a plane with said upper surface of said annular plate and extending radially therefrom to form an extension of the upper surface thereof, a post extending from the annular plate along a line substantially perpendicular to the plate, a disc of magnetizable material having an aperture to receive the post so that the disc is positioned adjacent the upper surface of the plate and ring and in magnetic circuit relation with the poles of said electromagnet, and said ring passing between said annular pole of the electromagnet and said disc to define a working gap between said annular pole and the upper surface of said ring having a magnetic reluctance less than said predetermined magnetic reluctance.

5. A device to develop controllable tension in a moving strand comprising an electromagnet including an an nular coil, a housing of magnetizable material for the coil forming an annular pole of the electromagnet, a central core of magnetizable material mounted within the annular coil and magnetically coupled to the housing, a relatively fixed annular plate of magnetizable material coupled magnetically to the central core and extending over a portion of the annular coil to form an opposite pole of the electromagnet and to define a gap of predetermined magnetic reluctance between the poles, the annular plate having an upper surface against which a moving strand is squeezed to apply tension thereto, a ring of non-magnetizable material fixedly mounted about the periphery of and having an upper surface lying in a plane with said upper surface of said annular plate and radially extending therefrom to form an extension of the upper surface thereof, a post extending from the annular plate along a line substantially perpendicular to the plate, a disc of magnetizable material having an aperture to receive the post so that the disc is positioned adjacent the upper surface of the plate and ring and in magnetic circuit relation with the poles of said electromagnet, said ring passing between said annular pole of the electromagnet and said disc, said ring having an annular groove to receive said annular pole to define a working gap between said annular pole and the upper surface of said ring, and said last-mentioned gap having a magnetic reluctance less than said predetermined magnetic reluctance.

6. A device to develop controllable tension in a moving strand comprising an electromagnet including an annular coil, a housing of magnetizable material for the coil forming an annular pole of the electromagnet, a central core of magnetizable material mounted in the housing within the annular coil and magnetically coupled to the housing, a relatively fixed annular plate of magnetizable material coupled in magnetic circuit relation to the central core and extending over at least a portion of the annular coil to form an opposite pole of the electromagnet and to define a gap of predetermined magnetic reluctance between the poles, said annular plate having an upper surface, a ring of non-magnetizable material fixedly mounted about and having an upper surface lying in a plane with said upper surface of said annular plate and extending radially therefrom to form an extension of the upper surface thereof, and a disc of magnetizable material positioned adjacent the poles of the electromagnet and in magnetic circuit relation therewith so as to be urged toward said upper surface of said annular plate and ring by the electromagnet for applying a controllable tension to a moving strand.

References Cited in the file of this patent UNITED STATES PATENTS 2,907,535 Mindhei m et a1. Oct. 6, 1959 FOREIGN PATENTS 926,861 Germany Apr. 25, 1955 

